Avalanche Forecast

Issued: Mar 8th, 2012 8:28AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Wind Slabs, Persistent Slabs, Deep Persistent Slabs and Cornices.

jeremy.mackenzie, Alberta Parks

Kananaskis.

Natural avalanche cycle up to size 3.0 continues. Wind loading was dramatic due to westerly winds at 140km/h at ridgetop. Moist snow on solar aspects this afternoon. Prime conditions exist for human triggering.

Summary

Confidence

Good

Weather Forecast

Light snowfall expected to begin late Friday morning. Freezing levels will climb to 1800m. Extreme wind speeds of 140km/h expected out of the west.

Avalanche Summary

Several new natural avalanches in alpine terrain up to size 3.0, mostly on N, E and SE aspects, and most running full path. Below treeline today two size 1.0 skier controlled avalanches were cut out by forecasters. These small slabs failed on the buried surface hoar down 50cm and occurred on N aspects at 1800m.

Snowpack Summary

Snowpack is settling rapidly with the warm temperatures. Solar radiation creating moist snow on solar aspects in the afternoon. Several large whumpfs felt today in moderate terrain. Two small skier controlled avalanches occurred in steep terrain on N aspect failing down 50cm on the Valentines surface hoar. Intense snow transport is occurring in the alpine due to persistent extreme winds out of the west.

Problems

Wind Slabs

Several layers of wind slab are present on lee and cross loaded features. A failure in these slabs will likely step down to the surface hoar or the basal facets. Large avalanches are occurring on this layer. Extreme west winds expected to continue.

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 7

Persistent Slabs

The Valentine's surface hoar and sun crust continue to be a problem The surface hoar is particularly touchy and is now buried an average of 120cm at treeline. Remote triggering, cracking and whumpfing continue to occur, as do natural avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 7

Deep Persistent Slabs

Weak facets and depth hoar linger at the base of the snowpack. Thin steep areas are the most likely trigger points. Large avalanches are stepping down to this weakness.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

3 - 7

Cornices

Cornices have grown significantly in the alpine. Failures continue to occur and have triggered avalanches up to size 3 on the underlying slopes. Give cornices a wide berth and stay well back from corniced ridge crests.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 6

Valid until: Mar 9th, 2012 8:00AM